Q and A: One of my dive buddies told me that if I blew an eardrum I could never dive again. Is this true?

Probably not. Many divers have ruptured an eardrum and returned to diving after recovery. In many cases the biggest problem is the fluid that gets in the ear and the resulting infection.
However, as with any injury you should see a Physician to determine what you need to do to be able to return to diving.
As an aside, over 15 years ago I was with a diver that blew his eardrum so badly that bubbles came out his ear. He recovered nicely and is still diving today.